1. Technical Field
The present invention relates to a gas turbine first-stage stator blade sealing structure in which leakage of air is reduced at the stator blade of a gas turbine.
2. Description of Related Art
FIG. 10 is a general section showing an arrangement of the blades of a gas turbine. As shown, reference numeral 31 designates a first-stage stator blade, the rear flange 32 of which is fixed in contact with a stator blade support ring 33 arranged in an arcuate shape around the rotor. A plurality of stator blades 31 are arranged in contact with the stator blade support ring 33 around the rotor. Numeral 34 designates a plurality of first-stage moving blades which are arranged on a rotor disc adjacent to the stator blades 31 so that they rotate together with the rotor. Similarly, numeral 35 designates a second-stage stator blade; numeral 36 designates a second-stage moving blade; numeral 37 designates a third-stage stator blade; numeral 38 designates a third-stage moving blade; numeral 39 designates a fourth-stage stator blade; and numeral 40 designates a fourth-stage moving blade. What is shown is an example of a four-stage gas turbine which has the stator blades and the moving blades alternately arranged so that the moving blades are rotated by the hot combustion gas.
FIG. 8 is a diagram showing the details of the first-stage stator blade 31, the rear flange 32 and the stator blade support ring 33 thus far described. While the gas turbine is being run, the stator blade support ring 33 is heated and thermally deformed due to the hot working gas such that the rear flange 32 and the stator blade support ring 33 move relative to each other thereby causing a fall, as shown. Then, the contacting faces partially lose contact with each other, as will be described, to make the inner seal of the first-stage stator blade 31 insufficient so that the sealing air 40 leaks.
FIG. 9 is a view taken in the direction of arrows IX--IX of FIG. 8. The rear flange 32 is arcuate along the stator blade support ring 33. The rear flange 32 and the support ring 33 are in contact with each other in the normal state. Since the stator blade support ring 33 is also circular, however, a crescent clearance is established, as shown, when the blade relative to the ring falls. This clearance is leakage area 41, through which the sealing air leaks to thereby increasing the flow of leaking air.
In the first-stage stator blade of the prior art gas turbine, as described hereinbefore, when the rear flange 32 of the stator blade 31 and the stator blade support ring 33 fall relative to each other due to the thermal stress during the operation of the turbine, there is established between the contacting faces of the two a clearance, through which the inside sealing air leaks so as to increase the leakage air. The leakage air is uselessly released to the combustion gas thereby deteriorating the performance of the gas turbine. Therefore, it has been desired to improve the sealing structure of especially the first-stage stator blade.